El Paso-TAMU Agr Res Cntr
Non Technical Summary
Salinity and water scarcityare the major challenges confronting sustainable development in many arid and semi-arid regions of the world. A majority of the irrigated area in Rio Grande basin is affected by salinity and sodicity. Salinity of Rio Grande has long been recognized as a major water-quality problem throughout the basin It is therefore important to manage soil and water salinity to reduce adverse impacts on agriculture and urban sectors for the economic and environmental well being of the region. Many arid regions affected by salinity are also regions that are facing increasing water scarcity. Water demands are increasing in the region, driven largely by rapid population and economic growth but supplies are stagnat or decreasing. Precipitation contributes little to the water availability and major source of irrigation is the Rio Grande River. The region is heavily dependent on mostly brackish groundwater for meeting its urban water demands. Therefore, it is important to improvewater use efficiency to conserve freshwater and develop alternative irrigation sources through water reuse in order to meet future agricultural/urban needs and to extend the availability of freshwater sources in the region.This project is aimed at developing appropriate salinity and watermanagement practices to ensure sustainability of irrigated agriculture,extend freshwater availability through water reuse andimprove on-farm water use efficiency to conserve freshwater.
Animal Health Component
Research Effort Categories
Goals / Objectives
The major objective of this project is to develop a set of efficient water and salinity management practices to ensure sustainability of irrigated agriculture and landscape water management. Specific objectives of the project are to: Assess extent and degree of salinity at the field scale and develop appropriate salinity management practices to ensure long-term viability of irrigated agriculture in the region. Develop appropriate techniques to facilitate environmentally safe reuse of waters with elevated salinity such as reclaimed wastewater, agricultural return flows, and gray water. Improve on-farm water use efficiency to conserve freshwater resources.
Objective 1: Salinity Assessment and Management Research will be conducted to develop data on distribution of salts and identify salinity hotspots within affected areas at field scale using traditional methods as well as electromagnetic induction techniques. Developing salt distribution information at field scale will aid in the development of appropriate salinity management practices and reduce cost of remediation by targeting application of amendments. Experiments will be conducted to study retention mechanisms of salts on the soil exchange complex. Suitable isotherm models will be used to provide quantitative description of salt exchange processes. Soil column experiments under controlled conditions involving different types of soils receiving water with varying ionic compositions, pH and ionic strengths will be conducted to determine salt adsorption and buildup in soil. Leachate samples will be collected and analyzed for chemical composition using standard methods (Eaton et al., 2005). Soil water movement, transport of salts will be evaluated using a suitable chemical transport model (e.g., Hydrus 3D). Results of these experiments will help in evaluating potential risks associated with transport of salts from the soil profile to underlying groundwater bodies. Performance of different amendments such as synthetic polymers or precipitated wastes from water supply pretreatment (predominantly inorganic flocculants such as aluminum or Iron salts) to ameliorate calcareous/gypsic sodic soils will be evaluated using soil column experiments. Since the project proposes the use of commercially available inexpensive polymers and industrial wastes such as water supply pretreatment wastes, it is hoped that these amendment technologies will be economically viable. Collaborative research with resource economists will be carried out to evaluate the cost effectiveness of different technologies utilizing amendments. Depending upon the efficiency of salt removal in root zones and cost effectiveness, these amendments will be evaluated using field experiments involving suitable experimental design (use of amendments such as water supply pretreatment waste may be subject to permitting requirements). Research in collaboration with plant scientists (e.g., Dr. Genhua Niu/ Dr. Calvin Trostle) will be carried out to evaluate remediation of calcareous sodic soils using plants. Collaborative research with irrigation engineers (e.g., Dr. Juan Enciso) will be conducted to develop appropriate irrigation methods to manage salinity. The results of these experiments will provide information on efficiency of different amendments in reducing the salinity in the root zones of major crops grown in the region. Objective 2: Water Reuse Potential for reuse of waters from different sources (such as reclaimed wastewater, desalination concentrate blends, graywater and power plant cooling tower reject water) for irrigating suitable plants will be evaluated under both controlled and field conditions. Column studies under controlled conditions involving different soil types receiving water with elevated salt concentrations will be used to evaluate changes in soil properties (permeability and salt concentrations), and to develop suitable management practices. Changes in soil salinity and moisture conditions will be monitored by direct soil sampling at different depths within root zones and also by using moisture/salinity probes. Chemical properties of wastewaters from different sources and leachate samples will be analyzed. Suitable soil salinity and sodicity management practices identified through different experiments conducted to achieve objective 1 will be implemented to minimize the adverse effects of reuse of water with elevated salinity. A suitable chemical transport model will be utilized to understand salt transport through the soil profile receiving water with elevated salt concentrations to assess potential for groundwater contamination. The results of these experiments will be useful in determining appropriate management practices for use of water with elevated salinity. Objective 3: Improving on-farm water use efficiency to conserve freshwater Improved irrigation scheduling will be developed using readily available inexpensive real-time continuous soil moisture sensors. The performance of different soil moisture sensors will be evaluated in the laboratory. Based on the outcomes of laboratory examination, the best performing moisture sensor will be installed in select fields representing variations in soil types encountered in the irrigation district (EPCWID#1). Data collected from soil moisture sensors will be utilized to predict the lower limit or threshold soil moisture level to trigger irrigation. Given the challenges growers face in the irrigation district regarding the uncertainty about the time of water delivery, it is important to determine when the soil moisture will be at the threshold level several days in advance. This project will develop a method using daily evapo-transpiration data available (free of cost) on Texas ET network (http://texaset.tamu.edu) to decide when to order irrigation water. Amount of irrigation water applied using improved irrigation scheduling will be compared to that by traditional methods of irrigation scheduling to compare water savings. Results of this project will be widely disseminated through grower meetings, extension agents, project factsheets, presentations at scientific meetings, and technical articles to encourage wider adoption of improved irrigation scheduling in major crops grown in the region (pecan, alfalfa and cotton) to save irrigation water.